The Mad Men starlet and Body of Proof star were joined by a big group of friends, including Michael Cera, at Stone Rose lounge in New York City.

"They were acting cute and she was giggling," an onlooker tells PEOPLE of the pair. "It was adorable how Geoffrey was being sweet with her and totally doting. I was surprised Michael was with them, but they must know each other well because it seemed like they were close."

And in typical Mad Men fashion, the actress sipped on vodka martinis throughout the evening. – Dahvi Shira